Non-pneumatic tire and other annular devices
A non-pneumatic tire for a vehicle or other machine. The non-pneumatic tire may include an annular beam. The annular beam may include a plurality of layers of different elastomeric materials. The annular beam may be free of a substantially inextensible reinforcing layer running in a circumferential direction of the non-pneumatic tire. The annular beam may include a plurality of openings distributed in the circumferential direction of the non-pneumatic tire. Such an annular beam may be part of other annular devices.
1. A wheel component comprising:
a non-pneumatic tire comprising:
a tread;
an annular beam disposed radially inwardly of the tread, configured to deflect more by shearing than by bending at a contact patch of the non-pneumatic tire, and comprising a plurality of layers of different elastomeric materials; and
a tension-based annular support disposed radially inwardly of the annular beam and resiliently deformable such that, when the non-pneumatic tire is loaded, an upper portion of the tension-based annular support above an axis of rotation of the non-pneumatic tire is in tension; and
a hub disposed radially inwardly of the tension-based annular support;
wherein: a ratio of the transverse deflection of the annular beam due to shear over a transverse deflection of the annular beam due to shear over a transverse deflection of the annular beam due to bending at a center of a design contact length is at least 1.2 when an outermost radial extent of the annular beam is loaded against a substantially flat surface over the design contact length; and the non-pneumatic tire is unreinforced between the tread and the tension-based annular support.
2. The wheel component of claim 1 , wherein a modulus of elasticity of a first one of the different elastomeric materials is different from a modulus of elasticity of a second one of the different elastomeric materials.
3. The wheel component of claim 2 , wherein a ratio of the modulus of elasticity of the first one of the different elastomeric materials over the modulus of elasticity of the second one of the different elastomeric materials is at least 2.
4. The wheel component of claim 3 , wherein the ratio of the modulus of elasticity of the first one of the different elastomeric materials over the modulus of elasticity of the second one of the different elastomeric materials is at least 3.
5. The wheel component of claim 2 , wherein the modulus of elasticity of the first one of the different elastomeric materials is at least 150 MPa and the modulus of elasticity of the second one of the different elastomeric materials is no more than 50 MPa.
6. The wheel component of claim 5 , wherein the modulus of elasticity of the first one of the different elastomeric materials is at least 200 MPa and the modulus of elasticity of the second one of the different elastomeric materials is no more than 30 MPa.
7. The wheel component of claim 1 , wherein: a first one of the layers of the annular beam is made of a first one of the different elastomeric materials;
and a second one of the layers of the annular beam is disposed radially inwardly of the first one of the layers of the annular beam and is made of a second one of the different elastomeric materials that is less stiff than the first one of the different elastomeric materials.
8. The wheel component of claim 1 , wherein: a first one of the layers of the annular beam is made of a first one of the different elastomeric materials; a second one of the layers of the annular beam is made of a second one of the different elastomeric materials; a third one of the layers of the annular beam is made of the first one of the different elastomeric materials; and the second one of the layers of the annular beam is disposed radially between the first one of the layers of the annular beam and the third one of the layers of the annular beam.
9. The wheel component of claim 8 , wherein the first one of the different elastomeric materials is stiffer than the second one of the different elastomeric materials.
10. The wheel component of claim 1 , wherein a radially-outermost one of the layers of the annular beam and a radially-innermost one of the layers of the annular beam are made of a first one of the different elastomeric materials; and an intermediate one of the layers of the annular beam is disposed radially between the radially-outermost one of the layers of the annular beam and the radially-innermost one of the layers of the annular beam and is made of a second one of the different elastomeric materials.
11. The wheel component of claim 10 , wherein the first one of the different elastomeric materials is stiffer than the second one of the different elastomeric materials.
12. The wheel component of claim 1 , wherein the layers of the annular beam are arranged such that the different elastomeric materials alternate in a radial direction of the non-pneumatic tire.
13. The wheel component of claim 1 , wherein the ratio of the transverse deflection of the annular beam due to shear over the transverse deflection of the annular beam due to bending at the center of the contact patch is at least 2 .
14. The wheel component of claim 1 , wherein a contact pressure at the contact patch of the non-pneumatic tire is substantially constant over the contact patch.
15. The wheel component of claim 1 , wherein the ratio of the transverse deflection of the annular beam due to shear over the transverse deflection of the annular beam due to bending at the center of the design contact length is determined as:
z
s
z
b
=
19.2
EI
L
2
1
GA
where:
z s is the transverse deflection of the annular beam due to shear;
z b is the transverse deflection of the annular beam due to bending;
L is the design contact length;
A is a cross-sectional area of the annular beam;
EI is an effective product of a modulus of elasticity E and a moment of inertia I of the annular beam that is determined as ΣE i I i which is a sum of products of a modulus of elasticity E i and a moment of inertia I i of each of the layers of the annular beam; and
G is an effective shear modulus of the annular beam that is determined as 1/Σ(v fi /G i ) where v fi is a volume fraction and G i is a shear modulus of each of the layers of the annular beam.
16. The wheel component of claim 1 , wherein a contact pressure produced by the annular beam against the substantially flat surface is substantially constant over the design contact length.
17. The wheel component of claim 1 , comprising a plurality of spokes disposed radially inwardly of the annular beam and resiliently deformable such that, when the non-pneumatic tire is loaded, upper ones of the spokes above an axis of rotation of the non-pneumatic tire are in tension.
18. A wheel component comprising:
a non-pneumatic tire comprising:
a tread;
an annular beam disposed radially inwardly of the tread, configured to deflect more by shearing than by bending at a contact patch of the non-pneumatic tire, and comprising a plurality of layers of different elastomeric materials; and
a plurality of spokes disposed radially inwardly of the annular beam and resiliently deformable such that, when the non-pneumatic tire is loaded, upper ones of the spokes above an axis of rotation of the non-pneumatic tire are in tension; and
a hub disposed radially inwardly of the spokes;
wherein the non-pneumatic tire is unreinforced between the tread and the tension-based annular support.
19. The wheel component of claim 18 , wherein: a ratio of a transverse deflection of the annular beam due to shear over a transverse deflection of the annular beam due to bending at a center of a design contact length is at least 1.2 when an outermost radial extent of the annular beam is loaded against a substantially flat surface over the design contact length.
20. The wheel component of claim 18 , wherein a ratio of a modulus of elasticity of a first one of the different elastomeric materials over a modulus of elasticity of a second one of the different elastomeric materials is at least 2.
21. The wheel component of claim 18 , wherein a ratio of a modulus of elasticity of a first one of the different elastomeric materials over a modulus of elasticity of a second one of the different elastomeric materials is at least 3.
22. The wheel component of claim 18 , wherein a modulus of elasticity of a first one of the different elastomeric materials is at least 150 MPa and a modulus of elasticity of a second one of the different elastomeric materials is no more than 50 MPa.
23. The wheel component of claim 18 , wherein: a first one of the layers of the annular beam is made of a first one of the different elastomeric materials; and a second one of the layers of the annular beam is disposed radially inwardly of the first one of the layers of the annular beam and is made of a second one of the different elastomeric materials that is less stiff than the first one of the different elastomeric materials.
24. The wheel component of claim 18 , wherein: a first one of the layers of the annular beam is made of a first one of the different elastomeric materials; a second one of the layers of the annular beam is made of a second one of the different elastomeric materials; a third one of the layers of the annular beam is made of the first one of the different elastomeric materials; and the second one of the layers of the annular beam is disposed radially between the first one of the layers of the annular beam and the third one of the layers of the annular beam.
25. The wheel component of claim 18 , wherein the layers of the annular beam are arranged such that the different elastomeric materials alternate in a radial direction of the non-pneumatic tire.